Rolling bearing temperature measurement system in a railway axle-box and associated method

Abstract

A measurement system including: a radial external hole on a cover of a railway axle-box on the side of an edge of the cover facing towards a rolling bearing of the axle-box; a smaller axial hole made on the edge of the cover facing towards a ring of the bearing and opening in the radial hole; a cup-shaped body accommodated in the radial hole; a fork shaped spring integrally carried by a bottom wall of the cup-shaped body, projecting in front of the axial hole; a temperature probe slidingly accommodated within the axial hole and including a tubular element incorporating an electrical temperature sensor and an electric cable protruding from a first end of the tubular element accommodated within the cup-shaped body; and an abutting element removably coupled to the first end to cooperate with the spring, which pushes a second end of the probe out of the axial hole.

The invention claimed is: 
     
       1. A system for measuring temperature of a rolling bearing in a railway axle-box; the system comprising:
 the railway axle-box; 
 the rolling bearing; 
 a first hole made in radial direction with respect to a symmetry axis (A) of the rolling bearing externally on a cover of the railway axle-box on a side of an edge of the cover facing towards the rolling bearing; 
 a second hole having smaller diameter than the first hole and made in axial direction with respect to the symmetry axis (A) of the rolling bearing on the edge of the cover facing towards a ring of the rolling bearing cooperating in abutment against the edge of the cover, the second hole opening in the first hole; 
 a cup-shaped body accommodated in the first hole; 
 a spring integrally carried by the cup-shaped body that projects in front of the second hole, which is in direct communication with the interior of the cup-shaped body; 
 a temperature probe slidingly accommodated within the second hole and in turn comprising a tubular element longer than the second hole and carrying therein at least one electrical temperature sensor provided with an electrical connecting cable protruding from a first end of the tubular element, the first end overhangly accommodated within the cup-shaped body; and 
 a shoulder element integrally coupled to the first end for cooperating with the spring; 
 wherein the length of the second hole and of the tubular element, the shape of the spring and a coupling position of the shoulder element with the tubular element are selected so that the spring pushes the probe towards an extracted position in which a second end of the tubular element axially protrudes out of the second hole, and wherein 
 when the cover is arranged with the edge in abutment against the ring of the rolling bearing, the spring is preloaded and presses the second end of the tubular element of the probe against the ring of the rolling bearing. 
 
     
     
       2. The measurement system according to  claim 1 , wherein the cup-shaped body is accommodated in a first radial hole to leave an end portion of the first radial hole, opposite to a second axial hole; the measurement system further comprises a wireless transmitting head coupled at least in part with the end portion of the first radial hole; at least one electric cable protruding from the first end of the tubular element overhangly accommodated within the cup-shaped body connecting with the transmitting head. 
     
     
       3. The measurement system according to  claim 1 , wherein the first hole is a blind radial hole made in a peripherally outer portion of the edge of the axle-box cover, preferably but not necessarily immediately adjacent a seat for a bearing rotation speed sensor. 
     
     
       4. The measurement system according to  claim 1 , wherein the spring is a leaf spring and is integrally carried by a bottom wall of the cup-shaped body, in which bottom wall an L-bent end of the spring is preferably buried, the cup-shaped body being preferably made of a synthetic molded plastic material. 
     
     
       5. The measurement system according to  claim 4 , wherein the leaf spring projects from the bottom wall obliquely transversely to the bottom wall, to progressively approach a through hole made through a lateral wall of the cup-shaped body and arranged coaxial to the second hole, with respect to which the through hole has a diameter substantially identical or slightly greater; a fork shaped free end of the leaf spring is arranged facing the through hole. 
     
     
       6. The measurement system according to  claim 1 , wherein the shoulder element consists of an elastic stop ring, preferably of the Benzing type, inserted snap-wise in an annular groove made externally on a lateral wall of the tubular element, on the side of the first end thereof. 
     
     
       7. The measurement system according to  claim 6 , wherein the cup-shaped body is driven with interference into the first hole; the diameter of the first hole being adapted to allow the introduction and snap-wise mounting of the elastic stop ring into the cup-shaped body with the probe already slidingly inserted into the second hole and up to inside the cup-shaped body. 
     
     
       8. The measurement system according to  claim 1 , wherein the diameter of the second hole is about one order of magnitude less than the diameter of the first hole; the at least one electrical temperature sensor consisting of a thermocouple buried in the tubular element. 
     
     
       9. The measurement system according to  claim 1 , wherein the temperature probe comprises two electrical temperature sensors buried in the same tubular element and each provided with a respective electric cable. 
     
     
       10. The measurement system according to  claim 1 , wherein the measurement system comprises a wireless transmitting head that comprises:
 a first casing element defined by an internally hollow, pipe-shaped and box-like element, having one open end and a pedestal opposite to the open end and facing toward the first hole, the pedestal provided with a sleeve which overhangingly projects from the pedestal to couple with the first hole, within an end stretch of the first hole left free by the cup-shaped body; and 
 a second casing element which is cup-shaped and integrally and fluid tight joined to the first casing element in correspondence with the open end and closing the open end; 
 a pedestal bearing at least a pair of fixing screws to the cover. 
 
     
     
       11. A method for making a system for measuring temperature of a rolling bearing in a railway axle-box, comprising:
 making a first hole externally on a cover of the railway axle-box, with the cover removed from the railway axle-box, on a side of an edge of the cover facing towards the rolling bearing, the first hole being made in radial direction with respect to a symmetry axis (A) of the rolling bearing; 
 making on the cover edge, with cover removed from the railway axle-box, a second hole having smaller diameter than the first hole, the second hole being made in axial direction with respect to the symmetry axis (A) of the rolling bearing to be in use facing towards an outer ring of the rolling bearing cooperating in use in abutment against the cover edge, and so that the second hole opens into the first hole; 
 making, by molding a synthetic plastic material, a cup-shaped body delimited by a bottom wall and by a lateral wall perpendicular to the bottom wall and provided with a through hole, preferably co-molding into the cup-shaped body a leaf spring which projects into the cup-shaped body in front of the through hole; 
 driving with interference the cup-shaped body in the first hole, with the through hole aligned and coaxial with the second hole, which is thus put in direct communication with the inside of the cup-shaped body, with a free end of the leaf spring arranged facing the second hole; with cover removed from the railway axle-box, 
 mounting a temperature probe axially sliding in the second hole inserting it through an end of the second hole opposite to the first hole, to make a first end of the probe, provided with at least one electrical connecting cable overhangly insert into the cup-shaped body and leaving a second end of the probe, opposite to the first one, projecting from the edge of the railway axle-box cover out of the second hole; with the cover removed from the railway axle-box, 
 passing through the first hole, coupling a shoulder element integrally on the first end of the probe, the shoulder element being adapted to cooperate with the leaf spring for elastically deforming it when the second end of the probe is pushed in a fully retracted position into the second hole; and 
 mounting the cover closing the railway axle-box, so that the cover edge abuts against the outer ring of the rolling bearing pushing the probe in the retracted position. 
 
     
     
       12. A method according to  claim 11 , further comprising:
 assembling a wireless transmitting head having an analog-digital converter and an aerial enclosed in a casing; 
 connecting the wireless transmitting head to the temperature probe through the at least one electrical transmission cable; 
 coupling the wireless transmitting head in an end portion of the first hole, opposite to the second hole, left free by the cup-shaped body; and 
 fixing the wireless transmitting head to the cover.